Groundbreaking Work on Chromium in Groundwater

Posted on 08.23.2015

Prof. Tom Johnson and graduate student Andre Ellis have developed a way to monitor the mobility of chromium in groundwater. Chromium, a heavy metal commonly used in industrial applications such as electroplating and leather tanning, is the second-most abundant inorganic groundwater contaminant at hazardous waste sites. The oxidized, hexavalent state of Cr, Cr (VI), is toxic and soluble, so it can move easily in groundwater. The reduced state, Cr (III) can form a solid, precipitating out of solution, thus limiting its mobility. Also, Cr (III) is less toxic, and is a nutrient at low levels. Johnson and Ellis's new work relies on measurements of the 53Cr/52Cr isotope ratio-to determine this ration, the researchers had to develop new laboratory techniques. They found that the 53Cr/52Cr ratio increases systematically as Cr (VI) is reduced. Their observation was published in the March 15, 2002, issue of Science, and has captured the attention of consultants trying to characterize chromium-contaminated sites.